--> Abstract: Holocene Flooding History Linked to the Interplay of Eustasy, Sediment Supply, and Climate Change of a West Louisiana Bay, by Kristy T. Milliken, J. B. Anderson, and A. B. Rodriguez; #90039 (2005)

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Holocene Flooding History Linked to the Interplay of Eustasy, Sediment Supply, and Climate Change of a West Louisiana Bay

Kristy T. Milliken1, J. B. Anderson1, and A. B. Rodriguez2
1 Rice University, Houston, TX
2 University of Alabama, Tuscaloosa, AL

The transgressive and highstand depositional systems of the Calcasieu incised valley adjust to the interplay between eustatic sea level rise, offshore sediment supply variations, and fluvial climatic variations. These factors are superimposed on subsidence and well constrained antecedent topography. The purpose of this study is to isolate the controlling factor for different periods of the flooding history of Calcasieu Lake.

Eighty six kilometers of high-resolution seismic data and 7 continuous cores (<20 m length) were collected to examine the response of the bay to different forcing mechanisms. Seismic and lithofacies changes are remarkably similar to Galveston Bay for the early Holocene. In both bays, major flooding surfaces associated with back-stepping facies record dramatic environmental changes. Preliminary radiocarbon dates of the flooding events are consistent with well dated flooding surfaces in Galveston Bay. Middle to late Holocene depositional facies in the middle and upper areas of Calcasieu Lake are different from Galveston Bay. Seismic stratigraphy linked to core facies illustrates bay head delta facies in Calcasieu Lake at a time when middle bay muds dominate Galveston Bay. This suggests different controlling factors on deposition between the two bays.

The most recent sea level records from the Gulf Coast for the mid-late Holocene reflects slow continuous rise, which is inconsistent with our inital observations assuming that sea level rise is the cause of flooding events. Ongoing efforts include developing a more detailed radiocarbon stratigraphy for Calcasieu Lake. Better chronostratigraphy will shed light on the forcing mechanisms that altered the bay environment.

AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005